Yesterday Sunnie and I spent all day at UNF watching the sculpture students participate in a large iron pour. Jenny Hager, Associate Professor of Sculpture at UNF had invited all the members of the Northeast Florida Sculptors group to check things out and since I had only seen casting on film, I thought it would be good to watch.
The pour was supposed to be from 12-3PM. We got there at 12, but things were already underway. It was clear that the melting furnace was the core of the operation.
A couple of other things were also clear. First, pouring iron is a serious undertaking. There were a lot of students there, all clad in leathers, with heavy boots, faceshields and gloves and every person had an assigned role. Second, we knew this was going to be a very hot day.
While they were getting the furnace up to speed we were checking out the scratch blocks that they were offering as a fundraiser. Scratch blocks are like half a mold with the casting sand stabilized with resin to make them pretty hard. However, if you scratch a design into them, you get a relief image when they pour in the iron. Both Sunnie and I decided to give it a try, since we’d never done anything like this before. We each got our block and started at it. I had brought an image from home, but Sunnie wanted to freehand it.
We turned in our scratch blocks and went to check out the pouring process, since the scratch block were going to be the last things poured. After all this pour was really for the sculpture students. They had quite a lot of molds prepped for pouring.
This was only a partial batch, since they only had so much space and each mold had to be leveled on a bed of sand. Molds were of all different sizes, including some that were quite large. Everything had to be set up just right, since once the pour started they had to be easily able to move from one mold to the next.
They were very precise about keeping track of everything. The iron was predominantly broken up cast iron bathtubs. The fuel that was being used was coke and every time the furnace was opened and a bucket of one of the materials went is, they sang out what was going in the furnace and another person would sing it out as well as she recorded the number of coke and iron buckets being fed into the furnace. There were a number of people working the furnace clearing slag and clinker and other people checking the status of the iron. As you can imaging there were a lot of impurities from the enamel coating on the bathtubs, so all that needed to be removed.
Once the iron came up to heat, a crucible was placed under the spout and the clay plug broken out to let the melted iron flow.
The filled crucible was then taken to a staging area where the dross was skimmed off to get pure iron for the pour.
There was a person in charge of each crucible’s pour. They had mapped out the path from the staging area to the mold, which molds they were going to fill and helped guide the people with the crucible. Safety was key.
There was a fire crew that when with each pour. Their role was to ensure that any spilled iron or iron from a leaky mold was quickly covered up with sand to prevent the wood most of the molds were mounted on from catching fire, to say nothing of preventing the pouring crew from stepping into some molten iron. Some of the molds were pretty hard to pour.
Leaky molds, while few, seemed to be the worst since all the iron poured into the mold would pour out at the seam until someone could get some sand or Kaowool in place to block the flow until solidified enough to block the molten iron.
After pouring quite a few molds it was getting harder to get the iron flowing from the furnace, so they would oxygen lance the furnace.
Pretty soon they were ready to work on the scratch blocks. There was a frame set up and leveled to make the pouring quicker. The blocks were all laid out and the pour would proceed from one to another.
They were still pretty hot and since there were so many to pour they had to wait a little, then move the solidified, but very hot molds scratch off to the side and set up and pour another group.
Finally all the casting was done. Forty pours in all I think. It was now 6PM, so Jenny’s crew had put in a long, hot and tiring day. The furnace was then broken down and cleaned.
It takes a village to pour some iron.
The scratch molds were broken up and the castings cooled with a hose and it wasn’t long before we were on our way.
It took a little wire brushing when we got home, but I’m pretty pleased with our first attempts. I think we’d both like to try this again.